1. Field of the Invention
The present invention relates to a lighting apparatus of a vehicle.
2. Description of the Related Art
A variety of lighting apparatuses of a vehicle have been proposed, for example JP-2005-329883-A. The lighting apparatuses each include a housing receiving an electric bulb and a busbar attached to the housing for connecting the electric bulb and an electrical cable.
Referring to FIG. 9, a lighting apparatus of a vehicle includes a pair of busbars 100A and 100B which are connected to positive and negative electrodes of an electric bulb through electrode connection portions 101. Electrical power is supplied to the electric bulb through electrical cable connection portions 102 connected with electrical cables.
The electrical cable connection portions 102 each are longitudinally connected with one end portion of the electrode connection portion 101 and each include a strip-shaped bottom wall 103 and a pair of piercing blades 104. The bottom walls 103 extend in a longitudinal direction of the electrical cable connection portions 101. The piercing blades 104 are upstanding from opposite ends in a width direction and have slits 105 therein. The piercing blades 104 of the electrical cable connection portions 102 are force pressed into an electrical cable 200 to accept core wires 202 into the slits 105 as shown in FIGS. 11-12. The electrical cable 200 is a flat cable having a plurality of core wires 202 juxtaposed each other and covered with an insulation cover 201.
The busbars 100A and 100B of FIG. 9 as described above are formed by bending busbars 100A′ and 100B′ of FIG. 10 a whole of which is stamped out of one electrically conductive metal plate. The stamped busbars 100A′ and 100B′ have a bridge 110 to avoid displacement of the relevant portions when stamping or bending thereof. The bridge 110 thereof is cut out when the busbars are formed.
As depicted in FIG. 9, both piercing blades 104 of the busbars 100A and 100B are not lined up in a width direction thereof or shifted in the longitudinal direction of the bottom walls 103 in order to make insulation displacement contact with the associated core wires 202. The one bottom wall 103 of the busbar 100B extends longer than the another bottom wall 103 of the busbar 100A.
The conventional lighting apparatus having the busbars 100A and 100B has several drawbacks as described below.
The busbars 100A and 100B extend along the longitudinal direction of the electrode connection portions 101, so that the dimension of the lighting apparatus becomes relatively larger.
Pitch of the core wires 202 of the flat cable 200 has recently become narrower to make the flat cable lightweight and more compact. The stamped busbars 100A′ and 100B′ thus have the piercing blades 104′ which are shifted each other in the longitudinal direction of the bottom walls 103′ so that the piercing blades 104′ are not overlapped each other as shown in FIG. 10. It is difficult to make the pitch P between the slits 105 of the conventional busbars 100A and 100B as small as the pitch of the core wires 202 of the flat cable 200.
Several methods are disclosed to achieve the insulation displacement contact for the flat cable 200 having the narrow pitch of the core wires. FIG. 11 shows that the piercing blades 104 are force contacted the outer core wires 202 among the three core wires 202 and the center core wire 202 runs between the piercing blades 104. FIG. 12 shows that the pitch of the core wires 202 is spread by cutting and opening the insulation cover 201 of the flat cable 200 to allow piercing of the piercing blades 104.
In order to narrow the pitch P between the slits 105 of the busbars 100A and 100B, the stamped busbars 100A′ and 100B′ can be further separated each other in the width direction. However, this causes reduction of yield of the electrically conductive metal plate, resulting in increase cost of production of the busbars 100A and 100B.